These Thread Sealants Are A Variation Of Our Basic RectorSealÆ No. 5 Formulation Modified For Specific Applications Where Low Odor, Non-Staining, and Soft Set Features Are Desired. RectorSealÆ No. 5 Special Is Especially Formulated For Use Around Gas Detection Equipment. RectorSealÆ No. 5 Sub-Zero Is Especially Formulated For Low Temperature Applications and Is Brushable To -35? F. They Are Non-Toxic In Accordance with NSF Standard 14 and/or Other Applicable NSF Standards. They Are Listed Under the Uniform Plumbing Code (IAPMO) File No. 1282. In Addition, they Are Approved and Listed with the Canadian Standards Association (CSA).